A Hierarchical Strategy for Real-Time Tracking On-Board UAVs

in ICUAS 2012 : 2012 International Conference on Unmanned Aircraft Systems (2012, June)

In this paper, we present a real-time tracking strategy based on direct methods for tracking tasks on-board UAVs, that is able to overcome problems posed by the challenging conditions of the task: e.g ... [more ▼]

In this paper, we present a real-time tracking strategy based on direct methods for tracking tasks on-board UAVs, that is able to overcome problems posed by the challenging conditions of the task: e.g. constant vibrations, fast 3D changes, and limited capacity on-board. The vast majority of approaches make use of feature-based methods to track objects. Nonetheless, in this paper we show that although some of these feature-based solutions are faster, direct methods can be more robust under fast 3D motions (fast changes in position), some changes in appearance, constant vibrations (without requiring any specific hardware or software for video stabilization), and situations where part of the object to track is out the field of view of the camera. The performance of the proposed strategy is evaluated with images from real-flight tests using different evaluation mechanisms (e.g. accurate position estimation using a Vicon sytem). Results show that our tracking strategy performs better than well known feature-based algorithms and well known configurations of direct methods, and that the recovered data is robust enough for vision-in-the-loop tasks. [less ▲]

On-board and Ground Visual Pose Estimation Techniques for UAV Control

in Journal of Intelligent and Robotic Systems (2011), 61(1-4), 301-320

In this paper, two techniques to control UAVs (Unmanned Aerial Vehicles), based on visual information are presented. The first one is based on the detection and tracking of planar structures from an on ... [more ▼]

In this paper, two techniques to control UAVs (Unmanned Aerial Vehicles), based on visual information are presented. The first one is based on the detection and tracking of planar structures from an on-board camera, while the second one is based on the detection and 3D reconstruction of the position of the UAV based on an external camera system. Both strategies are tested with a VTOL (Vertical take-off and landing) UAV, and results show good behavior of the visual systems (precision in the estimation and frame rate) when estimating the helicopter's position and using the extracted information to control the UAV. [less ▲]

Visual Servoing for UAVs

in Fung, Rong-Fong (Ed.) Visual Servoing (2010)

A Robotic Eye Controller Based on Cooperative Neural Agents

in Proccedings of World Congress on Computational Intelligence (WCCI 2010) (2010)

A neural behavior initiating agent (BIA) is proposed to integrate relevant compressed image information coming from others cooperating and specialized neural agents. Using this arrangement the problem of ... [more ▼]

A neural behavior initiating agent (BIA) is proposed to integrate relevant compressed image information coming from others cooperating and specialized neural agents. Using this arrangement the problem of tracking and recognizing a moving icon has been solved by partitioning it into three simpler and separated tasks. Neural modules associated to those tasks proved to be easier to train and show a good general performance. The obtained neural controller can handle spurious images and solve an acute image related task in a dynamical environment. Under prolonged dead-lock conditions the controller shows traces of genuine spontaneity. The overall performance has been tested using a pan and tilt camera platform and real images taken from several objects, showing the good tracking results discussed in the paper. [less ▲]

Fuzzy Controller for UAV-Landing Task Using 3D-Position Visual Estimation

in Proccedings of World Congress on Computational Intelligence (WCCI 2010) (2010)

This paper presents a Fuzzy Control application for a landing task of an Unmanned Aerial Vehicle, using the 3D-position estimation based on visual tracking of piecewise planar objects. This application ... [more ▼]

This paper presents a Fuzzy Control application for a landing task of an Unmanned Aerial Vehicle, using the 3D-position estimation based on visual tracking of piecewise planar objects. This application allows the UAV to land on scenarios in which it is only possible to use visual information to obtain the position of the vehicle. The use of the homography permits a realtime estimation of the UAV's pose with respect to a helipad using a monocular camera. Fuzzy Logic allows the definition of a model-free control system of the UAV. The Fuzzy controller analyzes the visual information to generate altitude commands for the UAV to develop the landing task. [less ▲]

Visual servoing using fuzzy controllers on an unmanned aerial vehicle

in EUROFUSE 2009. workshop on on preference modelling and decision analysis (2009, September)

This paper presents an implementa- tion of three Fuzzy Logic controllers working in parallel onboard a UAV, two for a pan-tilt camera platform and the third for control the yaw of the helicopter. This ... [more ▼]

This paper presents an implementa- tion of three Fuzzy Logic controllers working in parallel onboard a UAV, two for a pan-tilt camera platform and the third for control the yaw of the helicopter. This implementation uses a Lucas-Kanade tracker algo- rithm with a pyramidal optical ow implementation, which gives infor- mation to follow statics and moving objects, besides the UAV vibrations and movements. The platform con- troller is helped by the heading con- troller, in order to make smooth the big movements to the platform, re- ducing the risk of lost the warp selec- tion of the object to track. Also, the heading control remove the physic limit of the platform at the yaw axis. Some laboratory and UAV tests are presented in order to show the differ- ent behaviors and the good response of the presented controllers. [less ▲]

Trinocular Ground System to Control UAVs

in 2009 IEEE-RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (2009)

In this paper we introduce a real-time trinocular system to control rotary wing Unmanned Aerial Vehicles based on the 3D information extracted by cameras located on the ground. The algorithm is based on ... [more ▼]

In this paper we introduce a real-time trinocular system to control rotary wing Unmanned Aerial Vehicles based on the 3D information extracted by cameras located on the ground. The algorithm is based on key features onboard the UAV to estimate the vehicle's position and orientation. The algorithm is validated against onboard sensors and known 3D positions, showing that the proposed camera configuration robustly estimates the helicopter's position with an adequate resolution, improving the position estimation, especially the height estimation. The obtained results show that the proposed algorithm is suitable to complement or replace the GPS-based position estimation in situations where GPS information is unavailable or where its information is inaccurate, allowing the vehicle to develop tasks at low heights, such as autonomous landing, take-off, and positioning, using the extracted 3D information as a visual feedback to the flight controller. [less ▲]

Computer Vision Onboard UAVs for Civilian Tasks

in Journal of Intelligent and Robotic Systems (2009), 54(1-3), 105-135

Computer vision is much more than a technique to sense and recover environmental information from an UAV. It should play a main role regarding UAVs' functionality because of the big amount of information ... [more ▼]

Computer vision is much more than a technique to sense and recover environmental information from an UAV. It should play a main role regarding UAVs' functionality because of the big amount of information that can be extracted, its possible uses and applications, and its natural connection to human driven tasks, taking into account that vision is our main interface to world understanding. Our current research's focus lays on the development of techniques that allow UAVs to maneuver in spaces using visual information as their main input source. This task involves the creation of techniques that allow an UAV to maneuver towards features of interest whenever a GPS signal is not reliable or sufficient, e. g. when signal dropouts occur (which usually happens in urban areas, when flying through terrestrial urban canyons or when operating on remote planetary bodies), or when tracking or inspecting visual targets-including moving ones-without knowing their exact UMT coordinates. This paper also investigates visual servoing control techniques that use velocity and position of suitable image features to compute the references for flight control. This paper aims to give a global view of the main aspects related to the research field of computer vision for UAVs, clustered in four main active research lines: visual servoing and control, stereo-based visual navigation, image processing algorithms for detection and tracking, and visual SLAM. Finally, the results of applying these techniques in several applications are presented and discussed: this study will encompass power line inspection, mobile target tracking, stereo distance estimation, mapping and positioning. [less ▲]